The avian embryo: A developmental research tool

The importance of the chick embryo in embryological research is well known. Several authors have pointed out its applicability, advantages and usefuln ess in developmental biology, experimental embryology and teratology. The c hicken embryo is a proven animal model to screen drugs for their teratologi cal potential. Test solution is applied through a small hole drilled into t he shell above the air sac. This method reduces the mortalities associated with piercing the vitelline membrane. Volumes of up to 50 mul can be admini stered directly onto the vitelline vessels for rapid absorption. Several ex perimental groups can thus be treated quickly and efficiently with various concentrations of the drug of interest. Detailed analysis of the effects on a specific stage or structure is possible by terminating development at th at particular stage. Allantoic and amniotic fluids can be aspirated and ana lysed for specific metabolic products or markers. From the results it is ap parent that chemical interference is more recurrent in the development of c ertain structures as some effects, like ectopia. cordis and retarded growth , are seen repeatedly, irrespective of the substance tested. The effects ma y or may not be dose dependent. In conclusion, our results indicate that th e developing chick embryo is indeed a valid and sensitive developmental res earch tool in a well-controlled experimental environment.